Betta Heater This aquarium heater should be 100% submerged in water, ideal for small desktop glass or acrylic aquariums up to 1 to 6 gallons, not suitable for a tank of less than 1 gallon. Quick and easy installation: vertical or horizontal placement using, automatic temperature control of the aquarium heater 78 , no need to adjust the temperature, easy to operate, happy fish. How it works: Plug in, the red light will turn on, the heater will start to work until the water temperature reaches 78 F and the red light goes out, then the green light will come on, the heater will stop working and remain constant temperature 78 F. Accuracy 3 F Note: Do not operate or leave the product plugged in when your water tank is running out of water, the water heater must be completely submerged in water. It is best to install a water pump to help water circulate while heating. SATISFACTION GUARANTEED Our aquarium heater is designed with durability and safety in mind in every design. In the event that you are not satisfied with our product, contact us and we will gladly provide you with a new replacement aquarium heater. 12-month warranty and 24-hour professional after-sales service. "